“Well of course his hat! What else?” Jackaby shook his head in exasperation and gave a curt nod toward one of his leather volumes that lay in the wet moss. “Maybe if you would bother reading a book once in a while instead of hurling them about every chance you get, you would have put the pieces together yourself by now.” He sighed. “What we have been battling is a creature called a redcap,” he explained at last.

“The redcap is a horrible goblin who usually haunts the ruins of old castles, especially in Scotland and England. They’re antisocial beasts. It is unheard of to find one in a bustling metropolis, but as times change, so must we all, I guess. I was right about my first instinct as well. His magic is ancient. Redcaps are old creatures, nearly immortal if they tend to their namesakes properly.” He waggled the glistening hat as if in explanation, and a thick, sticky drip fell to the earth.

“I should have caught on much sooner—stupid of me. All of it fits with your descriptions, but I’d never met the man, myself, not until tonight. Those silly drawings of him in the newspaper don’t look a thing like him, of course. The polio braces were a nice bit of misdirection, I must admit. Covered the sound of his shoes and drew attention, while his fairy glamour helped him hide in plain sight. That’s classic, old magic, glamour. He kept the telltale signs, though—clearly not ready to give up his traditions. Redcaps stand apart from most of their fairy brethren in their immunity to iron, which, historically, they flaunt by wearing heavy iron shoes and wielding an iron spear or pike. He kept his hidden as a cane, but Swift had the lot, the arrogant bastard, and I missed it all.”

“Don’t feel bad,” I offered. “I met him face-to-face, and I missed it, too.”

“Yes, but no one expected you to be clever, Miss Rook.”

“Thanks for that,” I said.

“We got him in the end, at least. That’s something.”

“So, how do we finish this?” I asked. “You said it’s his hat that’s keeping him alive?”

“The blood,” answered Jackaby. “So long as the cap is kept wet with fresh human blood, he will not die. That’s why he had to keep finding new victims.”

“What are you waiting for, then? Burn the horrible thing!”